Goyangi wa Gae wa Neukdae ui Samgakgwangye

After blinking a few times, suddenly Ko Ihyun is twenty nine. Life hasn’t exactly been a waste… but he’s lonely.
Because he’s only ever gone for one-night stands, he’s earned himself the shameful reputation of being easy.
Then one unlucky day, he ends up running into two people at once—the younger guy who went down on him five minutes after they met, and his first love who broke up with him three years ago.

It’s officially the worst day ever.

(Source: MangaDex)